Firing indicator for internal combustion engines



Feb. 12, 1935. McLEOD r AL 1,990,835

FIRING INDICATOR FOR INTERNAL COMBUSTION ENGINES Filed July '7, 1932 I, l i I, O

U. Hilary )2 W M Patented Feb. 12, 1935 PATENT OFFICE FIRING INDICATOR FOR INTERNAL COMBUSTION ENGINES 1 Murdock McLeod and John Allan, Winnipe Manitoba, Canada Application July 7, 1932, Serial No. 621,180

1 Claim. (01. 175-183) The invention relates to improvements in firing indicators for internal combustion engines and an object of the invention is to providean indicator on the dash or other prominent location of an automobile which will show visibly to the driver the condition of the spark plugs of the engine and indicate also definitely what spark plugs require attention. I

A further object of the invention is to arrange the device so that under normal driving conditions, it is not in use and such that when the driver finds that his engine" is notiunctioning properly, he can test the spark plugs by actuating a finger piece provided and when such .is done, the indicator will show on the dash what plugs are not functioning properly and the exact location of such plugs. V

A further object is to constructgthe entire device in a simple, durable and compact manner cost and introduced as partof' the standard equipment of an automobile.

With the above more important and other minor objects in view Which will become more apparent as the description proceeds, the inven-,

tion consists essentially in the arrangement and construction of parts hereinafter more particularly described, reference being had to the accompanying drawing, in which:

Fig. 1 is a perspective view ofthe device and showing the various electrical connections.

Fig. 2 is a perspective view of a portion of the dash. v f

Fig. 3 is an enlarged detailed horizontal sectional view at 33 Figure 2,

Fig. 4 is a vertical'sectional viewat 4-4 Figure 3.

Fig. 5 is an enlarged detailed vertical sectional view through the type of spark plug employed.

Fig. 6 is an enlarged detailed vertical sectional view through the upper end of the spark plug and showing the push pull connections used for the wires.

Fig. 7 is an enlarged detailed horizontal sectional view at 77 Figure5.

Fig. 8 is a view showing the wiring diagram.

In the drawing like characters of reference indicate corresponding parts in the several figures.

The engine of the automobile is indicated generally by the reference numeral 1 and may have any number of cylinders, it being simply a matter of duplicating certain parts of our invention to accommodate the number of. W1-

and so that it can be sold at comparatively small inders. The engine shown is a four cylinder engine and is accordingly equipped with four similar spark plugs 2, 3, 4 and 5; These spark plugs are screwed into the engine head in'the usual manner and are for the greater part of ordinary construction as will be apparent from an inspection of Figure 5 where it Will be observed that the porcelain body 6 has the lower end received within the customary shell 7 and held therein by the bushing 8. i I

The porcelain body has the upper end thereof projectingabove the bushing and provided .at' diametrically opposite sides with vertical channels 9 and '10, the lower ends of which terminate just above the bushing in horizontal faces to engage lock nuts later described. Through the body of the porcelain, we pass two electrodes'll and 12 which have their lower ends inturned but spaced to provide a gap across which theusual firing spark jumps. v

The upper end of the electrodes are provided within the channels 9 and with extensions 13 and 14 of lesser diameter than the lower ends and the electrodes are held in place by bottom collars 15 secured to the electrodes and engaging the lower end of the porcelain and by top nuts 16 screw threaded onto the electrodes and en-. aging the lower closed ends of the channels.

The upper extensions of the electrodes are received within insulating ribs 17 and 18 contained within the channels and formed as part of an insulating cap 19 which encloses the upper end of the porcelain. The cap is provided at. its upper end with two pockets 20 and 21.,into which the upperends of they extensions of the electrodes pass and the extension 13 of the electrode 11 has its upper end screw threadedinto a metallic sleeve 22 contained within: an insulat ing sleeve 23 received Within the pocket 20. The pocket 21 contains also an insulating sleeve 24 and this carries two internally screw threaded socket like members 25 and 26 which have their 7 inner ends spaced apart to provide a spark gap 27. The lower socket member receives the upper screw threaded end of the extension 14 of the electrode 12. Spring contacts 23and 29 are screw threaded one into the upper end of the sleeve 22 and the other into the upper socket 26 and these spring contacts present each a pair of opposing spring jaws adapted to receive a ball 30 formed, at the ends of the wires leading to the electrodes. It will be observed that the upper ends of the insulating sleeves surround the spring contacts.

According to the construction of the spark 11 of the spark plugs to the dash and there con- 1. nect with a special device shortly described andv from this device, further wires 34 lead back and The device proplug just described, 'it will be apparent that to and from the upper ends of the electrodes' Usually there is only one wire leading to each spark plug as one of the electrodes thereof is grounded to the engine. both electrodes are insulated from the engine.

The customary distributor isindicated by the tected by the absence of a spark or the observreference numeral 31 and from this distributor,

plugs. Further wires 33 lead from the electrodes are grounded to the engine. 7 videdon the dash is now described in detail.

.A casing 35 is provided, the casing being suit-.

ably fastened ,to the dash and being provided with a front glass 36and with a closure plate. 37 of insulating material. Within the casing be-. tween the glass and plate, we insert a further relatively thick strip o'finsulating material 38.

whichis slottedtoprovide four closed compartments 39 visible through the glass or window. In one end of the casing, ,wef screw thread a sleeve 40 which is provided with ajflng'er and thumb piece 41'. A rod 42 extends lengthwise of the casing and centrally crosses *thesevera'lg compartments, the rod havingthe one 'end squared as indicated at 42' and received within a complementary squared aperture provided in the end of the casing to, prevent rotation of,

the same and the other end rotatably received within the sleeve and provided with acircum scribing rib 43r0tatable withinthe sleeved According to this arrangement, when one turns the finger'piece, the slejev'e screws in or out in respect to the casing and as it moves, it carries 7 the rod with it but the rodis prevented from turning due tothe square end 42' and its" squared receiving aperture.

are connected'respectively to the wires 33 which lead to the electrodes 11 of "the several spark Under normal operating conditions, the contacts 45 and 46 will be engaged butfsh c auld the g In our case, however,

7 On the rod and more or less centrally within each compartment, we mount driver at any time think that his engine is not firing properly due to .possible trouble in the ,spark plugs, he will turn the thumb piece in a direction which will withdraw the contacts 45 away from those 46 thereby providing four gaps,

one for each spark plug. By observing the difierent compartments through the window, he can immediately tell if one. ormore of the spark plugs are not functioning." 'This being determined, such plug or plugs canbe examined and repaired or replaced with new ones.

It is desirable to have the wiring arranged so that immediately a faulty spark plug is deing of apoor spark in any compartment, the driver will know the exact spark plug which is not operating. This can be readily done byalways considering the front spark plug of the engine as number one and .those following as two, three and four and then connecting'the partment in an order such that when. say 'com partment two indicates trouble, that trouble willbe found at the second spark plug of .theengine numbering from the frontand so on with the others.

if" "f on i While we have entered into .a' detailed de scription of the various parts, it will be understood that they could be readily modified'without departing from the spirit of the invention as set forth in the appended claim.

It will be noted that the gaps 27 are betwee j the wires 32 leading from the distributor and the electrodes 12 of'the spark plugs so that the firing spark produced by the plug is intensified.

Whatwe claim as our invention is:' In a firing indicator for internal combustion engines,ja prominently mounted casing provided with a sight glass, an insulating member mounted' within the casing a and provided with a plurality of separate compartments visible through of the rod uponthe rotary mevement ofthe thumb piece, a conta'ct member located in the sulated therefrom, saidstationary contact and movable contact being oppositely opposed and spaced to provide spark gaps. I

MURDOCK. McLEOD. JOHN ALLAN.

compartment and movable with the rod but. in-. 1 

